scholarly journals Dandelion pappus morphing is actuated by radially patterned material swelling

2021 ◽  
Author(s):  
Madeleine Seale ◽  
Annamaria Kiss ◽  
Simone Bovio ◽  
Ignazio Maria Viola ◽  
Enrico Mastropaolo ◽  
...  
Keyword(s):  
Cell Walls ◽  
Functional Materials ◽  
Vascular Bundles ◽  
Structure And Properties ◽  
Simple Material ◽  
Critical Design ◽  
And Function ◽  
Material Swelling ◽  
The Relationship ◽  
Radial Arrangement

AbstractPlants can generate motion by absorbing and releasing water. Such motion often facilitates reproductive success through the dispersal of seeds and fruits or their self-burial into the soil. Asteraceae plants, such as the dandelion, often have a hairy pappus attached to their fruits to allow them to fly and in many cases, these can open and close depending on moisture levels to modify dispersal. Here we demonstrate the relationship between structure, composition and function of the underlying hygroscopic actuator. By investigating the structure and properties of the actuator cell walls we have identified the mechanism by which the dandelion pappus closes and developed a structural computational model that can capture observed pappus closing. This model was used to explore the contribution of differential material domains in the actuator function and the critical design features. We find that the actuator relies on the radial arrangement of vascular bundles and surrounding tissues including cortex and the floral podium around a central cavity. This allows heterogeneous swelling in a radially symmetric manner to co-ordinate precise movements of the pappus hairs attached at the upper flank. This actuator is a derivative of bilayer structures, but is radial and can synchronise the movement of a planar or lateral attachment. The simple, material-based mechanism presents a promising biomimetic potential in robotics and functional materials.

scholarly journals II.—The microscopical features of mechanical strains in timber and the bearing of these on the structure of the cell-wall in plants

1921 ◽  
Vol 210 (372-381) ◽  
pp. 49-82 ◽  
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Cell Walls ◽  
Research Laboratory ◽  
Permanent Deformation ◽  
Structure And Properties ◽  
Mode Of Failure ◽  
The University ◽  
University Of Manchester ◽  
The Relationship

When wood is subjected to increasing mechanical stress its component parts ultimately undergo changes resulting in permanent deformation or failure. This paper deals with the minute microscopic changes upon which the permanent deformation of wood depends, and with the relationship between the microscopic structure of wood and some of its more important mechanical properties. The work has provided abundant material for a study of the structure of the walls of the cells of which wood is composed. Considerable light has been thrown on the structure and properties of the vegetable cell-wall in general, and it has been possible, from the facts for wood, to frame a hypothesis which seems to explain satisfactorily most of the properties of cell-walls. The examination of the mode of failure in timber, which has led to the work described in this paper, was begun at the request of Lt.-Col. Jenkin, R. A. F. I am deeply indebted to him for the original suggestion of this line of work and for his continued interest during its course. I have derived great advantage throughout the work by discussing various engineering questions, as they have arisen, with Major Robertson, R. A. F., and I desire to thank him for many helpful suggestions. I am further indebted to him for the supply of many fractured specimens of wood. The research has been carried out, in the course of more definitely applied work for the Air Ministry, in the Barker Cryptogamic Research Laboratory of the University of Manchester. I have to thank Prof. W. H. Lang, F. R. S., for encouraging me to attempt to relate the facts of the mechanical properties of wood to fundamental botanical questions bearing on the structure of cell-walls in plants.

Scanning tunneling microscopy (STM) of DNA and RNA

1989 ◽  
Vol 47 ◽  
pp. 34-35
Author(s):  
Patricia G. Arscott ◽  
Gil Lee ◽  
Victor A. Bloomfield ◽  
D. Fennell Evans
Keyword(s):  
Molecular Structures ◽  
Inorganic Materials ◽  
Resolving Power ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Form And Function ◽  
Dna And Rna ◽  
Calf Thymus ◽  
And Function ◽  
The Relationship

STM is one of the most promising techniques available for visualizing the fine details of biomolecular structure. It has been used to map the surface topography of inorganic materials in atomic dimensions, and thus has the resolving power not only to determine the conformation of small molecules but to distinguish site-specific features within a molecule. That level of detail is of critical importance in understanding the relationship between form and function in biological systems. The size, shape, and accessibility of molecular structures can be determined much more accurately by STM than by electron microscopy since no staining, shadowing or labeling with heavy metals is required, and there is no exposure to damaging radiation by electrons. Crystallography and most other physical techniques do not give information about individual molecules.We have obtained striking images of DNA and RNA, using calf thymus DNA and two synthetic polynucleotides, poly(dG-me5dC)·poly(dG-me5dC) and poly(rA)·poly(rU).

Physicianship and the Rebirth of Medical Education

2018 ◽  
Author(s):  
J. Donald Boudreau ◽  
Eric Cassell ◽  
Abraham Fuks
Keyword(s):  
Medical Education ◽  
Educational Process ◽  
Medical Attention ◽  
Patient Centeredness ◽  
Goals Of Medicine ◽  
The Subject ◽  
Definition Of ◽  
And Function ◽  
William Osler ◽  
The Relationship

This book reimagines medical education and reconstructs its design. It originates from a reappraisal of the goals of medicine and the nature of the relationship between doctor and patient. The educational blueprint outlined is called the “Physicianship Curriculum” and rests on two linchpins. First is a new definition of sickness: Patients know themselves to be ill when they cannot pursue their purposes and goals in life because of impairments in functioning. This perspective represents a bulwark against medical attention shifting from patients to diseases. The curriculum teaches about patients as functional persons, from their anatomy to their social selves, starting in the first days of the educational program and continuing throughout. Their teaching also rests on the rock-solid grounding of medicine in the sciences and scientific understandings of disease and function. The illness definition and knowledge base together create a foundation for authentic patient-centeredness. Second, the training of physicians depends on and culminates in development of a unique professional identity. This is grounded in the historical evolution of the profession, reaching back to Hippocrates. It leads to reformulation of the educational process as clinical apprenticeships and moral mentorships. “Rebirth” in the title suggests that critical ingredients of medical education have previously been articulated. The book argues that the apprenticeship model, as experienced, enriched, taught, and exemplified by William Osler, constitutes a time-honored foundation. Osler’s “natural method of teaching the subject of medicine” is a precursor to the Physicianship Curriculum.

From self-evident norms to contingent couplings: A systems-theoretical analysis of changes in the relationship between schools and the function systems in Denmark

2021 ◽  
pp. 147490412110097
Author(s):  
Niels Åkerstrøm Andersen ◽  
Justine Grønbæk Pors
Keyword(s):  
Theoretical Analysis ◽  
Education System ◽  
Teaching Profession ◽  
School Governance ◽  
World Society ◽  
Historical Account ◽  
And Function ◽  
The Relationship ◽  
Point Of Departure

Taking a point of departure in the paradoxical fact that the increase in educational knowledge leads to an increase in uncertainty for educational organisations, this article explores how uncertainty and contingency have increasingly become an integral part of school governance. The article draws on Niklas Luhmann’s theory of ‘World Society’ as a functional differentiated society providing a range of different symbolic media for educational organisations. To trace the increase in the complexity of governing, we provide a historical account of the shifting couplings between schools and function systems. We show how the school becomes linked to an increasing number of symbolic media so that education becomes only one out of many other concerns. The article studies the consequences these shifting couplings have for how schools are governed and how they are expected to self-manage their relationship to different function systems. The article adds to existing studies of how education has become more and more differentiated with the argument that this has also led to new forms of couplings between schools and the education system with a number of important implications for the teaching profession.

scholarly journals Lung ultrasound presentation of COVID-19 patients: phenotypes and correlations

2021 ◽  
Author(s):  
Gianmarco Secco ◽  
◽  
Marzia Delorenzo ◽  
Francesco Salinaro ◽  
Caterina Zattera ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Lung Ultrasound ◽  
Structure And Function ◽  
General Ward ◽  
Prognostic Role ◽  
Interstitial Syndrome ◽  
Lung Structure ◽  
And Function ◽  
The Relationship

AbstractBedside lung ultrasound (LUS) can play a role in the setting of the SarsCoV2 pneumonia pandemic. To evaluate the clinical and LUS features of COVID-19 in the ED and their potential prognostic role, a cohort of laboratory-confirmed COVID-19 patients underwent LUS upon admission in the ED. LUS score was derived from 12 fields. A prevalent LUS pattern was assigned depending on the presence of interstitial syndrome only (Interstitial Pattern), or evidence of subpleural consolidations in at least two fields (Consolidation Pattern). The endpoint was 30-day mortality. The relationship between hemogasanalysis parameters and LUS score was also evaluated. Out of 312 patients, only 36 (11.5%) did not present lung involvment, as defined by LUS score < 1. The majority of patients were admitted either in a general ward (53.8%) or in intensive care unit (9.6%), whereas 106 patients (33.9%) were discharged from the ED. In-hospital mortality was 25.3%, and 30-day survival was 67.6%. A LUS score > 13 had a 77.2% sensitivity and a 71.5% specificity (AUC 0.814; p < 0.001) in predicting mortality. LUS alterations were more frequent (64%) in the posterior lower fields. LUS score was related with P/F (R2 0.68; p < 0.0001) and P/F at FiO2 = 21% (R2 0.59; p < 0.0001). The correlation between LUS score and P/F was not influenced by the prevalent ultrasound pattern. LUS represents an effective tool in both defining diagnosis and stratifying prognosis of COVID-19 pneumonia. The correlation between LUS and hemogasanalysis parameters underscores its role in evaluating lung structure and function.

The potential digestibility of cellulose in grasses and its relationship with chemical and anatomical parameters

1972 ◽  
Vol 78 (3) ◽  
pp. 457-464 ◽  
Author(s):  
R. J. Wilkins
Keyword(s):  
Floral Development ◽  
Lignin Content ◽  
Leaf Sheath ◽  
Vascular Bundles ◽  
Cellulose Digestibility ◽  
Wimmera Ryegrass ◽  
Rate Of Decline ◽  
The Relationship ◽  
Anatomical Parameters

SUMMARYPotential cellulose digestibility, measured by incubation in vitrofor 6 days, decreased during floral development in perennial ryegrass, Wimmera ryegrass, cocksfoot, oat and tall fescue. The rate of decline was slower than for cellulose digestibility measured after incubation in vitro for 2 days only. Morphological fractions ranked in order of descending potential cellulose digestibility – leaf blade, inflorescence, leaf sheath and stem.Lignin content was determined chemically by the method of Van Soest (1963) and lignified tissue was assessed by staining transverse sections of leaf blades and leaf sheaths with safranin and fast green. Both lignin and lignified tissue increased with maturity. Lignified tissue increased mainly through increase in the number of scleren-chyma cells, but was also affected by the formation of lacunae or cavities between the vascular bundles in leaf blades of cocksfoot and in leaf sheaths of all species studied. For 19 samples of leaf blades and leaf sheaths, potential cellulose digestibility had significant negative correlations with both lignin content (r = -0·862) and lignified tissue (r = -0·905). Limitations to the techniques used to assess lignification and further factors which may affect the relationship between lignification and potential cellulose digestibility are discussed.

scholarly journals RELATION OF ADRENAL CORTICAL HORMONE TO LYMPHOID TISSUE AND LYMPHOCYTES

Blood ◽  
1948 ◽  
Vol 3 (7) ◽  
pp. 729-754 ◽  
Author(s):  
WILLIAM N. VALENTINE ◽  
CHARLES G. CRADDOCK ◽  
JOHN S. LAWRENCE
Keyword(s):  
Adrenal Cortex ◽  
Lymphoid Tissue ◽  
Hormonal Control ◽  
Tissue Structure ◽  
Lymphoid Tissues ◽  
Adrenal Cortical Hormone ◽  
Cortical System ◽  
And Function ◽  
Relationship Of ◽  
The Relationship

Abstract The hormonal control through the hypophyseo-adrenal cortical system of lymphoid tissue structure and function is an important concept. We cannot at the present time regard that the concept is established fact. Final judgment must await additional work and the clarification of some of the inconsistencies which appear to exist. It seems reasonable that lymphoid tissue is one of the end organs of adrenal cortical hormone and that it may perhaps play a role in the response of the organism to stress. It seems quite clear that the sugar hormone of the adrenal cortex is capable of producing structural alterations in lymphoid tissue. Change in thoracic duct lymphocyte numbers as a result of augmentation in the amount of available adrenal cortical hormone is at present controversial. Experiments in this laboratory have failed to demonstrate it. The production of lymphopenia, at least in some species and possibly in man, by increasing available sugar hormone is supported by some evidence. The exact mechanism of production of lymphopenia is open to question, its relationship to changes in lymphoid tissue structure being one of inference. The converse situation—absolute lympocytosis resulting from deprivation of adrenal cortical hormone—is the subject of controversial reports. At best, it must be admitted that relatively slight alterations from the accepted normal range of lymphocyte values occur in the adrenal insufficient organism. Changes in plasma gamma globulins and antibody titers associated with changes in the amount of available cortical hormone are reported. It should be clarified whether such changes have necessarily resulted from lymphocyte dissolution or are related to other of the variegated actions of adrenal cortical hormone. The relationship of adrenal cortical hormone to lymphoid tissue and lymphocytes and the relationship of the latter to the response of the organism to stress must indeed be complex. It is reasonably well established that the life span of the lymphocyte is very short indeed1,58,22 and each lymphocyte presumably liberates its metabolically important contents within a few hours at the most. If stress continues for any period of time, as often it does, it is difficult to visualize the wisdom of interfering with the production of metabolically vital substances in order to secure the transient benefits of lymphoid tissue dissolution. It is also somewhat difficult to regard as proved that the various changes reported after hormone augmentation or deprivation necessarily represent the normal mechanism by which these factors are regulated and kept within physiologic limits. More investigations are required to answer such questions and to further elucidate the interrelationship of the adrenal cortex and lymphoid tissues.

scholarly journals Validating Linear Systems Analysis for Laminar fMRI: Temporal Additivity for Stimulus Duration Manipulations

2020 ◽  
Author(s):  
Jelle A. van Dijk ◽  
Alessio Fracasso ◽  
Natalia Petridou ◽  
Serge O. Dumoulin
Keyword(s):  
Systems Theory ◽  
Linear Systems ◽  
Blood Oxygenation ◽  
Ultra High Field ◽  
Feedback Information ◽  
Oxygenation Level ◽  
Early Visual Cortex ◽  
Magnetic Resonance Imaging Mri ◽  
And Function ◽  
The Relationship

AbstractAdvancements in ultra-high field (7 T and higher) magnetic resonance imaging (MRI) scanners have made it possible to investigate both the structure and function of the human brain at a sub-millimeter scale. As neuronal feedforward and feedback information arrives in different layers, sub-millimeter functional MRI has the potential to uncover information processing between cortical micro-circuits across cortical depth, i.e. laminar fMRI. For nearly all conventional fMRI analyses, the main assumption is that the relationship between local neuronal activity and the blood oxygenation level dependent (BOLD) signal adheres to the principles of linear systems theory. For laminar fMRI, however, directional blood pooling across cortical depth stemming from the anatomy of the cortical vasculature, potentially violates these linear system assumptions, thereby complicating analysis and interpretation. Here we assess whether the temporal additivity requirement of linear systems theory holds for laminar fMRI. We measured responses elicited by viewing stimuli presented for different durations and evaluated how well the responses to shorter durations predicted those elicited by longer durations. We find that BOLD response predictions are consistently good predictors for observed responses, across all cortical depths, and in all measured visual field maps (V1, V2, and V3). Our results suggest that the temporal additivity assumption for linear systems theory holds for laminar fMRI. We thus show that the temporal additivity assumption holds across cortical depth for sub-millimeter gradient-echo BOLD fMRI in early visual cortex.

The Story of the Samaritan and the Innkeeper (Luke 10:30-35): A Study in Character Rehabilitation

2009 ◽  
Vol 17 (4) ◽  
pp. 422-447 ◽  
Author(s):  
Bruce Longenecker
Keyword(s):  
Guiding Principle ◽  
Good Samaritan ◽  
History Of ◽  
Reign Of God ◽  
And Function ◽  
The Relationship ◽  
Interpretative Framework

AbstractThe aphorism 'context is everything' has been a guiding principle in many studies of Jesus' parabolic sayings. This is true, for instance, of studies attempting to recover a parable's significance in relation to the ministry of Jesus of Nazareth, or in relation to its literary placement and function, or in relation to its polyvalent potential. It is also true of this study, which examines Jesus' narrative of the Samaritan—usually referred to as the 'parable of the good Samaritan'. It suggests that, when the Samaritan story is placed within a certain contextual configuration, its narrative features align themselves in ways that have either been conspicuously neglected or consciously avoided in the history of the story's interpretation. Rather than neglecting or avoiding the significance of these narrative features, this essay seeks to exploit their interpretative significance in a fresh manner, entertaining possibilities of meaning beyond the Lukan interpretative framework. In particular, consideration is given to the relationship between the Samaritan and the innkeeper as representing an exceptional partnership that testifies to the reign of God in making each party vulnerable to loss while promoting goodness towards others.

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